Furnace door operating mechanism



Dec. 5, 1950 E. A. HANFF 2,532,841

FURNACE DOOR OPERATING MECHANISM 3 Sheets-Sheet 1 Filed April 22, 194"! .HLH M w M Dec. 5, 1950 E. A. HANFF ,53

FURNACE DOOR OPERATING MECHANISM Filed April 22, 1947 3 Sheets-Sheet 2 4 T: 12 W w I 1. 1 I I l I I INVENTOR [mm/P0 A. Hrf/ FF ATTO RN EY Dec. 5, 1950 E. A.,HANFF FURNACE DOOR OPERATING MECHANISM 3 Sheets-Sheet 3 Filed April 22, 1947 Patented Dec. 5, 1950 2,532,841 I FURNACE DOOR OPERATING MECHANISM Edward A. Hanfi, Pittsburgh, Pa., assignor to Swindell-Dressler Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application April 22, 1947, Serial No. 743,083 12 Claims. (01'. 110-176) The general object of the present invention is to provide an improved door or closure operating mechanism of a. type adapted for use in moving a furnace door or analogous closure into and out of the position in which it closes an opening in the vertical wall of a furnace or processing chamber, and for use in maintaining a relatively large sealing pressure between the closure and chamber structure, when the closure is in its closed posi tion. A door or closure of the type referred to usually comprises a metal framework and masonry, and is of such size that the door ordinarily weighs several thousand pounds. The maintenance of a gas tight joint between the chamber structure and the closure in the closed condition of the latter, requires a suitable sealing pressure force, which in some cases may be substantially greater than the weight of the door.

The invention relates particularly to closure operating mechanism for a furnace or processing; chamber closure which in each opening and each closing operation is moved vertically between a lower level at which the closure closes the doorway and a higher level at which all or a portion of the closure is above the doorway. A primary object of the present invention is to provide improved means for moving the closure horizontally toward and away from th doorway in a final closing operation and in an initial stage of the opening operation, respectively, so as to provide suitable clearance between the chamber structure and the closure while the latter is being moved vertically between positions in which it does and does not entirely close the doorway.

A specific object of the invention, of primary.

practical importance is to provide closure operating mechanism comprising hoisting and counter-weight devices connected to the closure by lever and link arrangements, so that the counterweight action will reduce the hoisting device power required to give the closure its vertical movements, and in which the counter-weight action is utilized in giving the closure its horizontal guided closing movements, and to provide the closure sealing effect needed, and in which the hoisting device gives the closure its horizontal opening movements, and in which the counterweight and hoisting device cooperate in giving the closure its vertical movements.

The present invention may be used with especial advantage in operating the doors or closure of furnace and processing chambers of various types including relatively heavy closures, and in which a tight joint between the chamber structure and closure, when-it is in its closed position,

is needed to prevent the escape of heat or to maintain a desired atmosphere within the furnace or processing chamber. In such cases, gaskets or resilient sealing strips may be employed to insure gas tight joints, and mechanical clearance between the closure and chamber structure during the vertical movements of the closure is then required to avoid injury to the gaskets and sealing strips, and such clearance is generally desirable to avoid wear and scraping of closures and chamber structures.

Heretofore, numerous closure operating mechanisms have been proposed for furnaces and processing chambers of the type with which the present invention may be used'with advantage, but all such prior arrangemets of which I have knowledge, are open to one or more objections which it is the object of the present invention to avoid.

The various features of novelt which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is a plan view of apparatus shown in Fig. 2;

Fig. 2 is a front elevation, with parts broken away, of a portion of a furnace including an embodiment of the invention;

Fig, 3 is a side elevation with parts broken away and in section, of apparatus shown in front elevation in Fig. 2;

Figs. 4 and 5 are sectional elevations taken similarly to Fig. 3, but showing parts in different relative positions; V

Fig. 6 is a plan'section taken on the line 66 of Fig. 3; and

Figs. 7 and 8 are diagrammatic elevations showing a door in different positions and indicating the is normally closed by a furnace door which is of conventional type for use in furnaces of the general type shown and comprises non-metallic refractory and heat insulating material mounted in a metallic frame structure. In the closed position of the door, its marginal portion of its inner face fits snugly against the door jamb and lintel portions of the outer wall of the furnace at the margin of the door opening C, and the weight of the door is supported by stationary horizontal track members I perpendicular to and extending away from the portion of the furnace wall below the doorway C.

The initial door opening and the final door closing movements are horizontal movements in the direction of the length of the track members I. To facilitate those movements,'the door is advantageously provided with rollers 2 which "are journalled in brackets 3 attache'd to the door and rest on the track members I. In the normal closed position of the door show-n in-Figs. 1, 2 and 3, the weight of the door is supported by the track members I through the rollers 2, and the door is pressed against the portion of the furnace wall "surrounding the-door openingC with a predetermined sealing pressure,

The sealing pressure is applied through bell crank levers d mounted on pivots Sanchored in the door structure and extending horizontally away from the vertical side edgesof the door.

Asshown, the-dooris provided ateach side with an upper lever 4 and a lower lever 4. Each lever "'4 has-a relatively short arm and a relatively long arm. The short arm of each bell-crank lever 4 carries a horizontal crank pin or cam portion 6 which extends into a stationary vertical guideway formed by the trough of a channel bar I. As shown, each crank pin 6 supports an antiiriction sleeve or roller which directly engages the guide bar 1. There are two channel bars I, "oneat each side of the doorand each rigidly'secur'ed to the furnace structure. As will be apparent, turning movements'of the-levers '4 which are counter-clockwise as seen'in Figs. :3 and 4, will'move the door from'its closed position shown in Fig. 3, into its "partially open position shown in Fig. 4, since the lever fulcrums are formed by the s'tationarychannelbars T. In consequence, any such counter-clockwise turning movement :given to a lever 4 results in a horizontal movement of the lever pivot '5 which is anchored in the door, in the direction to move :the door 'away from the furnace. Conversely, when the door is in the partially open position, shown in Fig. 4, clockwise turning movements of the levers 4,as seen in Figs. 3 and 4, move the door toward its closed position.

The door operating mechanism comprises two door operating members 8, one at each side of the door and each pivotally connected to the outer end of the long arm of each "of the two levers 4 at the corresponding side of the door. As shown, each door operating member 8 'is in the form of a vertically disposed rodzor bar with four collars or circumferentially extending flanges 9. One of the four collars carried by each member 3 is immediately above, and "another is immediately-below the outer end of the long arm of the upper lever! connected to the bar, and one of the other two-collars is immediately above and the other'is immediately below 'theouter'end of the long arm of the lower 'lever 4 at the same side of the-door. The long arm of'each lever 4 is formed with a passage '4' loosely receivingthe bar-like body of the corresponding .member 8, as is shown in Fig. 6. Each-dooroperating member 8 has its upper end pivotally connected to the arm illa, of a lever -I-pivotally connected tothe doorby a horizontal pivot pin pivot l l i I mounted in a bracket !2 secured to the upper end portion of the door D. Each lever it] has a second arm iilb longer than its arm Ella and at the opposite side of the lever pivot i l.

A counter-weight it at each side of the door is connected to the shorter arm iiia, of the lever H3 at that side of the door by a flexible element M which ordinarily is 'a wire rope. Each rope i4 runs over-a corresponding sheave iEwhich is journalled to turn about the axis of a horizontal pivot shaft 15' supported in a bracket it, mounted on an upper portion of the furnace structure at the corresponding side of the doorway C. Each rope it is connected to the corresponding lever is between the pivotal connection of the latter to the corresponding member 8 and the lever To move the door from its partially open position, shown in Fig. 4, into its closed position, shown in Fig. 3, each lever it) is turned clockwise about its pivot i i as seen in Figs. 3 and 4, by the turning force then transmitted to the lever i0 through the ropeit by the corresponding counter-weight i3. After the door reaches its fully closed position, the force which the counter-weight 13 transmits builds up a'seali'ng pressure which reacts through the'corresponding levers 4 and member 8 to neutralize the torque to which the corresponding lever H2 is subjected by the counter-weight ISvconnectedthereto.

The longer arm Hlb .of each lever iil is connected to the lower end ='of 'a wire rope H orother flexible element'which has an'upper endportion wound around and secured :to a cor-responding hoisting drum E8. The two hoisting drumsconnected to the levers ill 'at the opposite sides of the door, are mounted on a horizontal shaft i-9 journall'ed inbrackets il'supported by the upper portion of the furnace structure. A worm gear 2i attached to one'end of the shaft 'lil is operatively engaged by a worm .22 adapted to hemtated by the shaft 23 of a'door operating motor 24.

In the closed position of the doors, the hoisting ropes 'l l are not undertension, and the counter-weights l3 operate through the levers ill, opcrating-members 8, and levers etc-establish and maintain a sealing pressure between the furnace structure and the door. When the door D is to be opened, the mo'tor M 'isoperated to rotate the shaft '5 9 in the directiontoput'the hoisting-ropes H under tension and apply lifting forces to the longer arms Hlb of the levers 4'6. Since the combined weight of the two counter-weights 13 is something less than the weight of the door D, the first eiiectof thus putting the ropes 1 under tensionis to tilt the levers NJ out of the positions which they occupy when the door is closed as shown in Fig. 3, and in'to thepositions occupied when the door is displaced from its-closed p'osition as shown in Fig, 4. As each lever ML-shown in Figs. '3 and 4, is tilted counter-clockwise from the position shown in Fig. 3 to tlie'positi'on shown in Fig. 4, the corresponding operatingmember 8 is lowered and each lever 4 is turned counterclockwise and operated as a lever of the second class to turn about its crank pin portion 6 asa fulcrum. and'thereby apply a horizontal'opening force to the door B through its pivot 5.

The counter-clockwise turning movement of the levers l6 and t, as seen in Figs. 8 and 4,13'01'1- 'the levers 4.: illustration that the door shown in- Figs. 7 and 8 weighs 6100 pounds and the single counterelement II increases until the aggregate lifting force exerted by the ropes l 4-and ropes I'l slightly exceeds the Weight of the door. Thereupon the door begins to move upward to, and then through its intermediate position shown in Fig. 5, into its wholly open position in which the lower edge of the door may be at or near the top of the doorway C. When thereafter, themotor 24 is operated to lower the door D, no change in the angular positions of the levers 4 and i occur until the rollers 2 engage the trackways I and the tension of the ropes I'i diminishes as the weight of the door is transmitted to the trackways. As the tension of the ropes I7 diminishes, the counterweights I3 turn the levers ID, and thereby the 'levers 4 clockwise and thus move the door into reengagement with the furnace wall and rees-'- tablish the furnace sealing pressure. With the door operating mechanism shown in the drawings, the counter-weight action thus directly reduces the l ad on the hoisting motor 26, and

operates through the levers 4 to give the door its horizontal closing movement and to establish and maintain the desired sealing pressure when closed and partially opened position in which it is respectively shown in Figs. 3 and 5. In Figs. '7 and 8, the entire counter-weight action may be, and as shown is, due to a single counterweight I3a connected through a single rope or analogous flexible suspension element I4a to the arm IDa of a single lever IDA. The lever IDA of Figs. 7 and 8 replaces the two levers ID of .1

the arrangement shown in Figs. 1 to 6. The second arm I Db of the lever IDA is connected to the hoisting mechanism by a single rope or suspension element I'Ia. In Figs. 7 and 8, the

arm Illa of the lever IDA is assumed to be connected to each ofthe various levers 4. Equal portions of the force impressed on the lever IDA by the counter-weight is transmitted to each of It is further assumed by way of weight I3a weighs 5000 pounds, and that the arm ID?) of the lever IDA is about times as long as the arm IDa, and that the bell crank levers 4 are proportioned andarranged so that in the 'under tension, the counter-weight subjects the element I4a to a tension of 5000 pounds and thereby subjects the long arm of each of the four levers 4 to an upwardly acting force of l250'pounds. With the 3 to 1 ratio of the effective'lengths of the long and short arms of the .levers 4, and on the assumption that those arms are substantially vertical and horizontal, respectively, each lever 4* will then subject the'door to a sealing pressure of about 3750 pounds. In consequence, the aggregate door sealing pressure created by the 5000 pound counter-weight is 15,000 pounds. When thedoor D is suspended as shown in Fig.8, 5000 of the 6100 pounds door weight is balanced by the counter-weight I3a,

and the total lifting forcewhich the hoisting mechanism must supply to hold the door in the position shown in Fig. 8 is only 1100 pounds.

This, with the assumed 5 to 1 arm ratio of the lever IDA, means that a downwardly acting force of about pounds is applied to the long arm of each lever 4 when the closure D is not resting on the tracks I. With the levers IDA thus held in rigid relation to the door, and with the two levers 4 at each side of the door located at suitable different levels and engaging the walls of the channel bars I without unnecessary clearance, the suspended door D is held against undesirable horizontal or swaying movements.

It will be observed that while the levers 4 are out of engagement with stops 25, the aggregate down-thrust of 500 pounds on the long arms of the levers 4 provides an aggregate potential force of 1500 pounds which can be exerted by the short arms of the four levers 4 against the walls of the guideway formed by the channel bars I, if that force is needed to effect the horizontal movement of the door from its position shown in Fig. 8 to its position corresponding to that shown in Fig. 4. It will be understood that the weights and dimensions above stated are given by Way of illustration and example, and not by way of limitation, and that the invention may be used with advantage with. door and door operating mechanism weights and dimensions very different from those given above.

With the levers 4 arranged at the levels shown in Fig. 4, the guideway formed by the channel bars I must extend from a level adjacent to the bottom of the doorway C to a level appreciably above the top of the doorway, if the levers and guideway are to cooperate in maintaining the door in parallelism with itself in all conditions, as I now consider preferable. However, the invention is not limited to an arrangement in which the levers 4 are arranged to engage guideway portions located at the sides of the door- -way C, or to engage a guideway which extends downward below the top of the'doorway C;

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that'changes may be made in 1. The combination with structure comprising a vertical wall with an opening therein and a vertical guideway, of a closure movable in a substantially horizontal direction toward and away from said wall between a position in which said closure engages said wall and closes said opening and a second position in which said closure is spaced away from said wall, and movable vertically between said second position and a more elevated third position, lever means cpivotally connected to said closure,'means cooperating with said igui'deway sand actuated by said lever means 011 pivotal movement in one direction or in the opposite direction to create a force acting between said door and guideway and tending to simultaneously. m'ove both the top and the bottom portions of said closure respectively toward or away from said. wall, counter balancing means connected to and subjecting said lever means lto -a lifting cforcesnialler than the Weight of the closure and tending to turn said lever means in said one direction, a hoisting device connected to said lever means and :subj ecti'ng said ilever means 'to a :second :lifting force varying between a maximum greater, and a minimum less than the difference between the weight :of theclosure and the first mentioned lifting-force.andtending to @turn said lever means 'in:said opposite direction with a force increasing as said second lifting iorc'e increases, said second lifting force acting on said lever :means with sufficiently greater leverage than said :first lifting 'force'so that said lever is turned in said :opposite'direction before said second lifting force be'com'es equal to said difference.

2'. The combination with structure comprising a vertical wall with an opening therein and a vertical guideway comprising spaced apart guide surfaces-at different distances from said -wall of a closure .movable toward and away from said wall between a position in which said closure engages said well and closes said opening and a second position in which said closure is-spaced away from said wall, and movable vertically between said second position and .a "more elevated third position, flever means pivotally connected to said closure, means cooperating with said guideway comprising two bell crank levers at 'each side of the door and located at different levels, each of said levers being pivot'ally connectedto the door and havingonearz'nconnected to said lever aneansan'd having itsotherarm in engagement with said guideway, said levers being actuated by said lever means on pivotal :movement in-one direction or in 'the oppositedirection to create a force acting "between said -door and guideway and tending to move said closure respectively toward or away from said wall, counter balancing means connected to and subjecting said lever means to a lifting-force smaller than the weight of the closure and tending to turn said levermeans in said one direction, a hoisting device connected to said lever means and subjecting saidlever means tea-second lifting force varying between a maximum .greater, and'a minimum less than the difference between 'theweight of "the closure and thefirst mentioned lifting force and tending to turn said lever means in said' opposite direction with-a force increasing as said second lifting force increases, and secondlifting force actingonsaid lever means with sufliciently greater leverage thansaid first lifting force so that said lever is turned insaidopposite direction before said second lifting force becomes equal to said difference.

3. The combination with-a closure for anopening in a vertical wall of operating mechanism for said closure comprising a lever element pivotally connected to said closure, counter balancing means connected to said element and subjecting the latter to a first lifting force smaller than the weight of the closure and to a torque tending to turn said element in one direction, a hoisting mechanism connected to said lever ele- :ment and operable to subject the-latter to a secmid lifting :forcevarying between a value which is smaller, and a value which is larger than the difference between the weight of the closure and 'said first lifting force, and subjecting 's-aid element to a torque tending to turn the lever element in a direction opposite to the first mentioned direction, said counter balancing means andhoisting mechanism being connected to said lever element tooperate on the latter with such different leverages that the hoisting mechanism torque increases to equality with the counter balancing means torque as said second lifting forc'eincreases from its first mentioned value to a value less than the difference between the weight of the-closure and said first lifting force, and closure adjusting means mounted on said closure and actuated by turning movements of said element to exert-a horizontal thrust against a :fixed "object, and thereby move said closure horizontally toward said wall as said lever element is turned in said'opposite direction.

A. Thecombination with a closure for an-opening in'avertical wall of operating mechanism for said closure comprising a lever element pivotally connected to said closure, counter balancing means connected to said element and subjecting :the latter to a first lifting force smaller than the weight of the closure and to a torque "tending to turn said element in onedirection, 'a hoisting mechanism connected to said 'lever element and operable to subject the latter to a second lifting force varying between-a value which is smaller, and a value which is larger than the diiierence between the :weight of the closure and said first :lifting force, and subjecting said element to a torque tending to turn the lever element in a direction opposite to the "first mentioned direction, said counter balancing means and hoisting mechanism being connected to said lever :element to operate on-the latter with such different leverages that the hoisting .mechanism torque increases to equality with the :counter balancing means torque :as said second lifting force increases from its first mentioned :value to'a value less than the difference between the weight of :the closure and said :first lifting force, and closure adjusting means mounted on said closure andactuated by turning movements of 'said'ele- :ment to exert horizontal thrusts against a fixed .object and thereby move said closure horizontally :away from or toward said wall as said-lever'ele- .ment is turned in said one direction or in said opposite direction.

5. A combination as sp'ecified in claim 3 in which said lever element comprises a pair of levers, one adjacent each side of theclosur'e and each pivotally connected tosaid closure.

6. A combination as specified in 'claim 5 in which-said adjusting means comprise an upper adjusting leverand a lower adjusting lever :at :each side of the door andlink-connected to the levercomprised in said lever means and at the same side :of said closure.

7-. A combination as specified in claim 3, :in which said adjusting 'means comprises one or more levers, each v:pivotally connected to said :closure and link connected to :said lever element.

'8. The combination with structure comprising a vertical wall with anopening therein, 0f 'a'cl'osure movable in a substantially horizontal zdire'c- -tion toward and away from'said wall :between a position -in which said iclos'ure engages saidwall and closes said-opening and asecondrposition in whichsaid closureiis spaced awayirom said wall, -and:movable vertically between said-second. position and a more elevated third position, counter balancing means connected to and subjecting said closure to a first lifting force smaller than the weight of the closure, a hoisting device connected to said closure and subjecting it toa second lifting force variable between a value greater, and a value less than the difference between the weight of the closure and said first lifting force, and means responsive to variations in the relative lifting forces for simultaneously moving the top and bottom portions of said closure toward and away from said wall as said second lifting force decreases below and rises to equality with said difference.

9. The combination with structure comprising a vertical wall with an opening therein and a guideway, of a closure movable toward and away from said wall between a lower position in which said closure engages said wall and closes said opening and a more elevated position in which said opening is not closed, means for moving said door between said positions comprising counterbalancing means subjecting the closure to a lifting force less than the weight of the closure and hoisting means regulable to subject said door to a second lifting force varying between a maximum greater and a minimum less than the difference between the weight of the closure and the first mentioned lifting force, and means mounted on said closure and actuated by said counterbalancing means to cooperate with said structure in pressing said closure against structure with a force substantially greater than the weight of said closure on a predetermined reduction in said second lifting force.

10. The combination with structure comprising a vertical wall with an opening therein, of a closure movable toward and away from said wall between a first position in which said closure engages said wall and closes said opening and a second position in which said closure is spaced away fit) 10 from said wall, and movable vertically between said second position and a more elevated third position, means for moving said door between its different positions comprising counterbalancing means subjecting the closure to a first lifting force less than the weight of the closure and hoisting means operable to subject said door to a second lifting force varying between a maximum greater, and a minimum less, than the difference between the weight of the closure and said first lifting force, and means movably mounted on said closure and actuated by said counterbalancing means to cooperate with said structure in moving the closure from said second position into said first position on a prede termined reduction in said second lifting force.

11. A combination as specified in claim 9, in which the means movably mounted on said closure cooperates with said structure to hold said closure substantially parallel with itself in moving between its second and first positions.

12. A combination as specified in claim 9, in which said hoisting means actuates said means movably mounted on said closure tocooperate with said structure in moving said closure from its first poistion to said second position on a predetermined increase in said second lifting force.

EDWARD A. HANFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num: er Name Date 1,314,572 Coleman Sept. 2, 1919 2,045,662 Longenecker June 30, 1936 2,119,426 Douglas May 31, 1938 2,199,182 Leonard Apr. 30, 1940 2,254,900 Lessman Sept. 2, 1941 2,494,713 Longenecker Jan. 17, 1950 

